A typical coupling such as described in East German patent document 134,980, German published application 2,948,179 of Barth and Viets, German published application 2,020,178 of Ernst and Bangert, German published application 4,211,619 of Haarmann and Bremer, German published application 4,338,039 of Gassen, and German published application 195 43 130 of Haarmann, Bremer, and Rast has an inner part, normally a ring, adapted to be connected to an engine or motor output shaft and an outer part that is normally connected to a load, for instance a flywheel, although of course the driving and driven parts could be reversed. In order to allow for some limited misalignment of the centers of the inner and outer parts, they are interconnected by a plurality of links having inner ends connected to the inner part and outer ends connected to or forming the outer part.
Since the links must transmit torque between the inner ring and the outer part, while still permitting relative radial movement of the inner ring and outer part, the links do not extend perfectly radially between the inner and outer parts. Hence it is standard to provide elongated links that are of generally fixed length between their inner and outer ends but that can be flexed somewhat, and to orient these links so that they extend more angularly than radially. In above-cited German 195 43 130, for example, there are two pairs of links that extend perpendicular to each other. Thus when the inner part, for example, moves parallel to one of the pairs, the other pair will flex, and vice versa, all while the links will continue to effectively transmit torque between the inner and outer coupling-disk parts.
Such a coupling can be relatively bulky and incapable of, at the same time, transmitting considerable torque while compensating for considerable radial or axial misalignment. The links can rupture when overloaded, leading to total failure of the coupling.